Well, as I said, my TV displays Tempest just fine.  It's just a little fuzzy.  But it's extremely playable.  I can read the letters on the high scores, and I can see the bad guys coming at me.  At very high resolutions, it looks pretty good, but the frame rate is a little choppy (in the 30s, as opposed to 50+ at 480x360).  I just want to optimize it for my limited display, not make it look perfect.